Key Takeaways from Meituan’s Java Interview: Backend Questions & Learning Roadmap

Although my memory isn’t perfect, I recorded a fresh set of interview notes from my recent Meituan Java interviews.

Meituan First Round

Do you understand SOA and micro‑services?

How does a distributed system perform load balancing and locate the server that holds a resource?

Common load‑balancing strategies: round‑robin, random, least‑response‑time, least‑concurrency, hash.

Design a distributed load‑balancing cache system and quickly locate the responsible server (key partitioning, consistent hashing).

How to guarantee strong consistency between cache and database (using locks).

What problems can arise with HashMap under high concurrency (rehashing issues).

Explain the end‑to‑end process after entering a URL in a browser (DNS, ARP, routing, server processing, response, rendering, fetching dependent resources).

Reverse the order of sentences in a string (e.g., “ABC DEF” → “DEF ABC”).

Give any binary tree nodes a next pointer (reference to the original problem).

Have you used a reverse proxy?

Meituan Second Round

Ways for inter‑process shared memory (8 methods).

How to view network port status (netstat) and memory usage (top) on Linux.

How ConcurrentHashMap expands.

What are Java exceptions?

What happens if a runtime exception is not handled and how should it be handled?

Programming task: given 50 million ints, find the top 1000 largest numbers with 2 GB memory (maintain a min‑heap of size 1000, O(n log 1000) time).

Select m distinct integers randomly from n distinct integers with O(m) time and O(1) extra space (swap selected elements to the end).

How to optimise a slow SQL query (add indexes, add filter conditions, consider table sharding, focus on large‑data scans).

Experience with containers (Tomcat) and comparison with other servers such as Nginx.

Experience with dynamic proxies.

Meituan Third Round

Self‑introduction and description of data flow in your project (draw a diagram).

What books have you read?

Deep insights from the JVM (memory model, garbage collection, class loading).

What is stored in heap vs. stack? Where are static members stored? (method area)

Three most impactful tips from “Effective Java” and your interpretation.

Which area are you most proficient in? (Java core data structures)

Explain the internal implementation of HashMap.

Is HashMap thread‑safe? (No, ConcurrentHashMap is).

How does ConcurrentHashMap work internally? Each segment is a Hashtable.

Technologies used in your project (Spring).

Which Spring features did you use most? (Spring IoC).

Advantages of Spring, principle of Spring AOP, and how Spring achieves decoupling.

Understanding of List, ArrayList vs. LinkedList and their differences.

Swap two nodes in a linked list (implement code).

Given a linked list and an integer k, reverse the list in groups of k (example provided).

How MyBatis works after configuring XML files to perform database operations.

Interview Summary

What knowledge should a Java developer with some industry experience focus on today?

Learning roadmap (stay tuned for a surprise at the end):

Proficient use of Spring MVC.

Master object‑oriented design and common design patterns.

Skilled with MySQL, understand database fundamentals and performance tuning.

Familiar with RPC, Zookeeper, Dubbo, Spring Cloud.

Experience with distributed systems, caching, messaging, search mechanisms, and cluster architecture design.

Personal qualities: responsible, innovative, passionate about technology, and eager to explore.

Strengths: strong logical thinking, quick problem analysis, and effective issue resolution.